精细可分级视频编码技术研究

【作者】 李占林；

【导师】 林其伟；

【作者基本信息】 华侨大学 ， 信号与信息处理， 2008， 硕士

【摘要】 随着视频编码技术的发展和一系列视频编码标准的相继出台,视频编码技术在很多领域得到了应用,然而传统的面向存储领域的视频编码技术主要解决的是如何提高压缩编码效率。随着近年来互联网和多媒体技术的不断发展,人们对基于网络的视频传输需求越来越广泛,如何产生适应网络传输的码流就成为了视频编码中的关键问题。因此,视频编码的目的已经由以前单纯的提高压缩效率转向提高压缩效率与适应网络传输并重。精细可分级视频编码(FGS),因为其能有效地解决网络视频中存在的大数据量、带宽变化和丢包等问题,被视为网络环境下的一种很有前途的视频编码方案。本文的工作主要是针对FGS编码效率较低的缺点,在保证其精细可分级特性的前提下,研究提高其编码效率的方法。论文首先介绍了视频图像压缩的基本思想和关键技术,并简述了视频编码标准的发展历程和各种标准的特点,特别是H.264中的一些关键技术。之后总结了各种可分级编码的原理、方法和改进策略,尤其是精细可分级编码方法和针对它的各种改进方案。在此基础上本文将H.264编码与MPEG-4 FGS编码相结合,提出了一种新的FGS编码方法——基于H.264的FGS编码,它以H.264编码标准作为方案的基本层,MPEG-4 FGS的增强层作为方案的增强层,使它既具有了H.264的高压缩率,又具有了FGS的精细可分级特性。实验证明,与MPEG-4 FGS相比,这种方法明显的提高了编码效率,改善了视频图像的主客观质量。之后,本文又提出了两种新的FGS增强算法——水环扫描算法和肤色选择增强算法,分别对水环中心区域和肤色区域进行增强。实验表明,水环扫描算法能在不增加编码复杂度和不降低整幅图像的质量的前提下,明显的提高水环中心区域的质量,而肤色选项增强算法则能在适当降低整帧图像质量的条件下,明显提升肤色区域的视觉质量。更多还原

【Abstract】 While developing of video coding technology and a series of video coding standards coming on one after the other, video coding technology has been widely used in many fields. However, the major task of the traditional video coding technologies for storage-based applications is how to improve the coding efficiency. With the rapid development of Internet and multimedia technologies, the demand of video communication based on network has been more and more aboard, and how to produce a video streaming which can adapt to communication has been a key question for video coding technology, so the aim of video coding has changed from improving coding efficiency to paying equal attention to coding efficiency and communication. Fine granular scalability coding (FGS) can effective solve the problems of video streaming on network, such as great data quantity, change of band width and lose of packages, and hence is regarded as a promising video coding scheme in the Internet scenario.Because of the low coding efficiency of FGS, this paper’s work is looking for a method to improve coding efficiency while keeping scalable capability. This paper firstly introduced the principle of video compressing, key technology of video coding, development of coding standards and their essential characters. The introduction of essential characters in H.264 was in particular. This paper also introduced each scalable coding method, summarized theirs principles, methods and improvements, and especially introduced fine granular scalability coding and its improvements. In this foundation, this paper combined H.264 and MPEG-4 FGS, and proposed a new method of FGS --- FGS video coding base on H.264. This method use H.264 as the base layer and the enhancement layer of MPEG-4 FGS as the enhancement layer, so it have more high coding efficiency while keeping scalable capability. Experimental results show that, compare with MPEG-4 FGS, this method can obviously improve the efficiency of coding and improve the subjective and objective picture quality. Afterwards, this paper introduced two enhanced methods for FGS---water ring scanning arithmetic and skin color selective enhancement arithmetic, respective enhanced to the centre area of water ring and the area of skin color. The experiments proves that, the methods of water ring arithmetic can significantly improve the picture quality in the centre area of water ring while keeping the efficiency of the whole picture and coding complexity, and the method of skin color selective enhancement arithmetic can significantly improve the skin color area’s picture quality while propriety reducing the whole picture’s coding efficiency.更多还原